skchevota

Hey guys, I posted a thread on this a while back, I tryed a few things but have not found a solution yet. I am expiriencing drive train chater, or mor like truck bounce when taking off. I t is only when I an sliping the clutch , once the cluch is out all is good. If I take off in 1st its not bad, but In 2nd I have hit my head on the rear window!, It also chatters or shakes in reverse. I have new moter mounts, and tranny mount. I tryed taking off with the hood open to see what the moter was doing and it looked fine. It lifted a little on the left sid as it should and then sat there while it fells like the center of the truck is going up and down. I dont get it, the shifter also sits still. Maby frame flex, but why so violently? Or maby spring wrap? I am running 2002 f250
super duty rear springs, they came behind the power Joke so I dont see why they would have a problum here. The truck did not have much spring wrap and did not chatter at all with the LT1 and TH400, even in low range , But it also had no clutch. I hada my cluch out a few days after I put the truck together to change the rear main seal (doh) and it was clean,dry , no chattere marks, I surfaced the flywheel when I put it together, I tightened the presher plate in a criss cross patern, the whole nine yards, and it did this from the start? I dont want to go through the time and expence of traction bars if that is not the problem. Any Ideas?
THANKS

bgilbert

I bet your driveshaft angle is off the grid with that 9" lift. Do you have a single piece rear drive shaft? Any carrier bearings? Spring blocks?

skchevota

3" of it is body lift, one piece rear shaft , 3.5 " block, the angles are minimal, It was worse with the gasser, the trans sat higher in the frame, now the rear shaft has nearly a straigt shot, it dose not vibrate at all at any speed, only when slipping the clutch,once it is engaged, even from an idle it is smooth acceleration. I forgot it also chatters or shudders when I down shift to like 3rd gear from 30mph, if I get it down to where it is at Idle speed or just above when I let out the clutch it is smooth , but It also dose not slip the clutch? Junk clutch? spring wrap?

apwatson50

I think its your clutch.

andyr354

could be a pitted or warped flywheel. Though you said it looked fine...

It would vibe most the time if the driveline angles are wrong. With the lift, since this is a non-CV style driveshaft, the pinion should be on the same plane with the output of the transfercase. Might check that. Kinda hard to make a diagram on here but they should be parallel to eachother within 3 degrees, not the pinion pointing at the transfercase.

Tuckerdee

Obviously you have the very rare Nerf u-joint option to smooth out the vibrations of the cummins.

Anyway...did you have the 37" tires with your old setup? Larger tires essential are a longer lever-arm to aid in wrapping up your springs. Just a thought. I would get somebody to watch the rear axle and springs when you let out the clutch. Maybe they can see something. Will it chatter if you have it in 4WD? I don't know for sure, but I would expect, that if the rear springs are wrapping you would notice less chatter if your front axle is pulling as well.

Another thought. What sort of clutch linkage do you have? Hydraulic or cables and rods? If the lever ratios are wrong on a mechanical linkage setup, you could end up with a lot of pressure plate/fork travel compared with very little clutch pedal travel. This would make it hard to slip the clutch or engage the clutch slowly since there would be a very fine line between engaged and not engaged at the pedal.

Yet another thought. You said you had new motor mounts and new transmission mount. What are they from? Are they rated for the sort of torque you're throwing at them? If they're on the wimpy side...for a stock Cheby 350 or something...then you might end up with the chatter you describe.

skchevota

Yea., I had the 37"s before, I will try to see what it does in 4 wheel drive, the mounts are new for a 93 cummins, I fabed some frame mounts out of 1/4 " steel plate, I added Quite a few gusets and also an additional crossmember under the engine and tied the mounts to it. So I think Im ok there , for good measher I added a chain from moter to frame on the left side to keep from pulling the rubber apart if I am in low range in a high tork situation. The clutch linkage is hydraulic. I think I will get someone to watch the springs as I take off, or set up the video cam so I can see for my self.
Thanks for the Ideas

timb

Just from past experience, it sounds to me like oil on the clutch disc.that will make the clutch chatter on take-off worse than anything.